Tiffen 4.5" Round Drop-In (DI) Water White Ultra Circular Polarizer Filter. Ultra Pol - yet another Tiffen advance, helping cinematographers and videographers realize their creative vision. Tiffen Linear Ultra Pol and Circular Ultra Pol filters offer the best polarization effects available for professional motion picture and television work. They extract the maximum of unwanted glare from the scene and render crisp white clouds against a dramatically dark blue sky, like never before. Distracting reflections from water and windows become invisible with the magic of the Ultra Pol filter. As the photos make perfectly clear, without Ultra Pol, the woman is hidden; with Ultra Pol, her face is the beautiful focal point. While removing glare, you also insure richer, truer colors free from glare's whitewash effects. Ultra Pols get the most from any scene that calls for a polarizer. Some camera-related optics, like a video tap, employ a partially silvered mirror, or beamsplitter. This may require the use of a Circular Ultra Pol, which places a clear, quarter-wave retarder on the camera side of the filter, effectively de-polarizing the light being recorded, after the image enhancement is done. Circular Ultra Pol filters are suitable for virtually all situations; Linear Ultra Pol filters excel in traditional applications.